Utility providers employ various meters and corresponding measurement circuitry to monitor the amount of electrical energy generated by or distributed to various service locations. Such locations may be respectively characterized by one of many different single-phase or polyphase service types, corresponding to such common operating voltages as 120, 240, 277 and 480 volts (RMS). Some known electricity meters have been designed to function at all or a number of such common metering voltages, and are thus operable over a wide input voltage range. Due to industry standards that often require meter accuracy at a range from about twenty percent below the minimum metered voltage value to about twenty percent above the maximum metered voltage value, meters operable in a full wide input voltage range correspond to those that are fully functional in an overall range of about 96 volts to 576 volts (RMS).
Electricity meters typically include some sort of input circuitry for receiving voltage and current signals at the electrical service. Input circuitry for receiving the electrical service current signals is referred to herein as current acquisition circuitry, while input circuitry for receiving the electrical service voltage signals is referred to as voltage acquisition circuitry.
Many different components have conventionally been used in meter voltage current acquisition circuitry, including respective voltage transformer, active current transformer, and resistive voltage divider configurations. Resistive voltage dividers are quite convenient, but may present calibration issues unless precision components are employed. Previous resistive divider configurations have employed adjustable divider configurations including both manually adjustable potentiometer type devices as well as digitally controlled selectable resistor values.
Such resistive voltage dividers may perform satisfactorily for certain instances, but in other environments, such as those requiring a matched voltage division, providing a pair of precisely matched voltage dividers may prove difficult. Further, maintaining a matched division ratio over time may also be an issue due to environmental changes, aging of components, and other considerations.
As such, it is desired to provide shunt voltage measurement circuitry within feasible size and cost constraints, while also providing highly accurate measurement capabilities. While various aspects and alternative embodiments may be known in the field of electricity metering, no one design has emerged that generally encompasses the above-referenced characteristics and other desirable features associated with input circuitry acquisition in an electrical service and associated metering technology.